It is known to carry out an in-vivo measurement of an approximate tissue equivalent dose with miniaturized to thermoluminescence dosimeters in certain applications. A drawback, however, is this limitation to certain applications. In addition, the measurement results are only available after expensive evaluation of the thermoluminescense dosimeter at the earliest an hour after termination of the irradiation.
Furthermore, there are numerous proposals and investigations into fiberoptic measurements of the dose or, using semiconductor dosimeters in-vivo and on-line (U.S. Pat. No. 5,014,708 of May, 1991; H. Buker et al, Fiber-Optic Radiation Dosimetrie for Medical Application, SPIE, Vol. 1201, Optical Fibers in Medicine V. P. 419-429(1990); H. Buker et al., Physical Properties and Concepts for Applications of Attenuation-based Fiber-Optic Dosimeters for Medical Instrumentation, SPIE, Vol. 1648, Fiber Optic Medical and Fluorescent Sensors and Applications, P. 63-70(1992)).
According to the proposals and investigations, sensors are used whose material has an effective atomic number significantly deviating from the tissue or a reduced sensitivity. It is, however, a drawback that a precise measurement, especially in the case of photon radiation, is not possible since the material of the sensor always deviates from that of the tissue and the absorbed dose is material dependent. Further, the information regarding the tissue depth is not in principle available. It is therefore a drawback that the choice of material is limited.